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REFERENCE

layer

n. · v.
US //ˈɫeɪɝ// lay·er
  1. 1 a thickness of material (n.)
    B1 Intermediate

    a single thickness of something that covers a surface or sits between other things.

    a single thickness of a substance or material covering a surface or forming one of several levels in a stack.

    Example

    The cake had a thick layer of chocolate cream in the middle.

    Example

    Archaeologists carefully removed the top layer of sediment to reveal the well-preserved stone foundations of the Roman villa.
  2. 2 a level in a system (n.)
    B2 Upper Intermediate Academic Technical Computing

    one part or level of a complex system or idea.

    a distinct level within a hierarchical structure, such as a software architecture or a social system.

    Example

    The security system has several layers to protect your personal data.

    Example

    In the OSI model, the transport layer is responsible for end-to-end communication and error recovery between hosts.
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  1. 3 an egg-laying animal (n.)
    C1 Advanced Technical

    a bird or insect that is kept for the eggs it produces.

    a mature female animal, particularly a domestic fowl, kept specifically for egg production.

    Example

    The farmer kept a hundred layers to supply the local market with fresh eggs.

    Example

    The productivity of the layers began to decline as the winter days grew shorter and the temperature in the coop dropped.

  2. 4 to arrange in levels (v.)
    B1 Intermediate

    to put one thing on top of another in levels.

    to arrange or form something in distinct thicknesses or tiers.

    Example

    You should layer the vegetables in the dish before adding the sauce.

    Example

    The gardener recommended layering the compost with straw to ensure proper aeration during the decomposition process.
Etymology 1

Appears at first glance to be from Middle English leyer, leyare (“a layer of stones or bricks”), equivalent to lay + -er. In which case, ultimately identical to etymology 2 below. For the pronunciation compare prayer. However, this word layer (referring to a thickness of a material covering a surface) has also been argued to be from a respelling of an obsolete sense of the word lair that was once used by farmers, which had to do with soil. The connecting sense between the usual meaning of lair and the specialised farming meaning was: an area where cows typically rest, the ground being fertilised by their waste. Related to lie, ledger.

Etymology 2

From lay + -er.

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